Knight or Vitodens?

Perry_3

with large commercial to power plant sized boiler water treatment (actually entire steam cycle chemistry).

Toss in some low temperature process water treament issues as well.

The issues are really the same for all boilers. The higher the pressure and temperature, the more you have to worry about water purity and water treatment.

Certain materials also require speicific treatments as well. I.e.; you wish to minimize chlorine exposure to SS that will get hot - like a boiler HX.

Very low pressure boilers typical of home to small commercial used to do just fine with no water treatment - as long as you could live with the scale. Cast Iron and Steel also are robust material against clorine (the Marshfield plant that I worked in ran only water softning on the oldest, lowest pressure, and smallest boiler they had (this boiler was the size of a very small house - or a modern garage in this area).

In this thread the started indicated that he has very hard water - and is concerned with the amount of scale that would come out in his new boiler. A valid concern.

In my personal case I have very low "hard" water (relatively soft water) in my home because city water here comes from Lake Michagan; which is a lessor concern (but, well water in the area is pretty hard).

Kevin Callahan

Hi folks,
I'm about to replace an old boiler with a mod-con. I have high temperature baseboard heat in a 2400 sq. ft. house. My best effort at a heat loss calculation comes up at about 75k btus per hour even at -22.

My preferred choices are a Knight 105 or a Vitodens 100 boiler. (I have decided not to go with a Weil McLain Ultra because I have high mineral content water and am concerned about its effect on the aluminum HE.) I am also putting in an indirect hot water heater but otherwise have a simple layout of two heating zones.

The Knight offers a greater turndown ratio (5-1), including both a lower range and more btus at the top (21K-95K). It also adjusts water temp up to 190. If the graph on the manufacturer's info is correct, it is over 90% efficient even at high return temperatures and high load. It has sophisticated but user friendly controls. I have yet to see any negative comments about it, and there is lots of good feedback.

The Vitodens 100 is much simpler and requires outboard controls, neither of which is necessarily a negative. It has a narrower range of modulation (26K to 90k), and if its efficiency is similar to the curve shown on the V200 literature, it may be less efficient at both higher temperatures and full loads. The build quality and Viessmann heat exchanger appear to be outstanding, and the stainless steel-titanium alloy might reasonably be expected to outlast others. One concern is that the boiler automatically goes only to 176 degrees, which could be an issue for baseboard on a very cold day. Although it has a higher fixed limit, I am not certain whether the 176 adjustable limit could be manually overidden.

I think i would be happy with either, but once again thought that asking the experts on this excellent log might be
a good idea. What do you guys think? Am I on the right track? Any reason to choose one of these excellent products over the other, or is it just individual preference?
Thanks!

tim smith

Look at the Prestige Solo 110

Great product, low pressure drop, user friendly. All on board controls. No problems seen to date. Stainless. Good luck, Tim

hot_rod

Between those two choices

I have the most experience with the Lochinvar Knight. I have not had one leave me, or my customer in the cold. If the features you mentioned are top on your list, the choice is clear.

Be sure to address that "high mineral content" water before it goes into your new indirect tank. It will quickly lower performance as it coats the HX surfaces.

The new Lochinvar Squire would be a good tank to match with the Knight. it has a large diameter smooth HX coil, and a top cleanout port, if I'm not mistaken.

hot rod

Perry_3

Depends what you are looking for

I installed a Vitodens 200 a year ago in my house, and rejected the Knight at the time as the Vitodens 200 is the best of the best and had the right features for my house.

I also agree that the Vitodens 200 HX is the best designed and constructed mod/con boiler HX on the market - by a good margine. I understand they are using the same HX in the 100 (but you should verify that).

I considered the Triangle Tube Prestigue as also very good - but much to large for my house (even the smallest Vitodens 200 is to large). It is also likely to be more simple to connect to many home heating systems as you do not need primary/secondary circuits for the normal household heat loads.

I note that I am very suspicious of claims of high turndown rates (5:1 or higher) and the efficiency/longevity of these systems. I have spent most of my life dealing with large commercial boilers (up to power plant size) and 3:1 is easy to do, 4:1 can be done if you spend the money on the highly durable parts, and 5:1 is very difficult to do and maintain over the years on a one burner system (and these "experiments" are at places that don't even blink on spending a $million or so on a new control and burner assembly to get higher turndown ratios). Key issues is that you are asking something to work well for air and combustion flows from the smallest to the highest rate. Lots of history and many attempts have shown that it just does not work well past 4:1 on a single burner (and even 4:1 is tough to do for long term reliable equipment). I have no doubt that they can do it for a year or two; but past that I suspect that more maintenace will be required to be able to maintain those turndown ratios. Depending on how the boiler is constructed will determine if you loose the low or the high end (and I suspect you will loose the low end first).

I note that the Vitodens 200 has a turndown ratio, if I remember correctly, of just under 4. It is my understanding that the Vitodens 100 has a turndown ratio of about 3 as it does not have the more advanced burner design and controls that the 200 has. Both of these claims are entirely reasonable for long term operation.

I would be pleasanlty surprised to be proved wrong and be shown a high turndown burner assembly that last and last without any problems. The key problem is that none of the mod/con boiler designs are old enough to give any indication. Personally, I did not want to be an experiment on that issue.

I also believe that you are very wise to stay away from Aluminum block boiler HXs.

Your hard water will affect any boiler. If all you do is one fill and have no leakage it is not a problem. If you are constantly replenishing water you will have a more significant problem (and other problems to boot). You may need to use softened water (or partially soften water). I do not recommend use of distilled water as pure water is rather agressive unless buffered with the correct chemicals.

Perry (homeowner; power plant engineer)

Unknown

The Ultra's been out for more than two years Perry, and its turndown is almost exactly 5 to 1. I haven't heard of any endemic failures, have you?

Edit: it's also and aluminum heat exchanger. again, I'm not hearing about failures. is anyone?

Unknown

Hey Kevin,

If your house really needs that much heat, maybe you should look at the envelope first. That's averaging over 30 BTUs/sq ft... not very good.

Also I think the viessmann only goes to 167 (75 deg C), not 176 deg F. That's maximum temperature allowed by law across the pond.

I haven't seen too many baseboard installs that 167 wouldn't satisfy. Most are overradiated significantly and could even run cooler than that if sufficient flow is present. But then again, you might have a very high heat load. Just food for thought.

Perry_3

Lets see what happens after 5 to 10 years.

2 years is nothing.

In my opinion a home heating boiler should last - with minimal maintenance for over 10 years (and well over at that).

2 years is not nearly long enough to see these things.

In Europe, what I could find on most of the Al Block HX failures showed up in the 5 year range.

Now I am well aware that some people and some Mfr's feel that a boiler should last no more than 10 years.

Perry

hot_rod

Failed aluminum HXers

One of the boiler treatment specialists I know visited an Amercian boiler manufacturer recently. They were testing the various glycols and their effects on aluminum HXers. He claims to have seen first hand the damage inappropriate glycols or water chemistry can have on aluminum. In less then a years time, pin holes were showing up.

The lesson being don't fall for inexpensive AL or multi metal glycols. Stick with the brands the boiler manufacturers have tested. Let the boiler builders do the R&D, not you and your customer.

I believe the same would be true if the fill water was out of the acceptable range. Ph especially with aluminum.

Keep in mind copper and stainless steel boilers also have a tolerance level that can be exceeded. I'd shy away from softened water in a stainless boiler, knowing how poorly some softeners backwash the brine cycle

DI or DM water with the best hydronic conditioners is the proper way to protect your installs and the customers investment. You don't have a thick, heavy, bullet proof, cast iron vessel anymore when considering mod con choices

hot rod

Unknown

you said two years, I was just responding to your comment.. the Ultra has been out much longer than that. It's been about five years now, so we should be seeing those failures any day...

That assumes the HX wasn't in use anywhere else before here in the US as well, which I doubt...

Where is the info on the failures that you looked up? I"m not having any luck finding them. Obviously if there is a track record of actual failures, I would want to know about it..

Kevin Callahan

Thanks everybody! Here's my thought process on some of the points raised--

Tim, I did not include the Prestige because the contractor I want to use doesn't work with it, not because it too is not an excellent product. I'll take another look though. Similarly, the Weil-McLain Ultra may be great, but my water is very very high in minerals; it coats shower heads and regularly gums up the intake to my washing machine. Even if I load soft water initially, which i will, I'm concerned that residual minerals in the system or a careless refill could lead to problems.

Rob, the reason the heat loss is high is because I live in Anchorage, Alaska. The polar ice is melting and the glaciers are retreating, but it still gets cold in the winter! Also, you're right that the Vitodens 200 maxes out at 167 degrees, apparently a requirement of German law, but the 100 has a higher adjustable limit of 176. That would be fine 98% of the time but it might be nice to have some margin of error, similar to modestly oversizing the upper btu capacity. The Vitodens 100 has a "fixed" limit of 210 degrees, but I am not absolutely sure whether or how 176 could be exceeded, possibly either by a manual override or by the system simply calling for more heat. I'd be interested if anyone knows the correct answer.

Hot Rod, no question the Knight is an excellent fit in all respects and has an excellent reputation. It is also a newer design than the Vitodens 100 (which apparently has been used in Europe prior to recently becoming available here) with maybe less long term track record. Of course, a second or newer generation design may have less flaws and better features than some of the older ones. To me it comes down to whether the Viessmann quality and HE, and the admittedly crystal ball factor of a possibly longer life, should be decisive. I probably have to tell the contractor on Monday or Tuesday, and I'm still mulling it over.

Thanks again for all the responses!

tim smith

Re: Prestige

Tell your contractor this is a great boiler, serviceable and much larger passages in heat x than Vito, Knight or the like. I think for the value, the best condensor on the market. Sorry to the rest but JMHO.

Mike E_2

How about adding more baseboard

How about adding more baseboard (or other type of radiation) to your house. This will allow you to run lower temperatures all the time and thus achieve higher efficiencies.

As to Vitodens 100 vs. Knight - for what it's worth, in the near future when I put in a mod con (in place of a Vaillant oil boiler) I plan on putting in a Knight.

Michael

Paul Rohrs_7

Curious about the Vito 100

I have only read literature about the Vitodens 100. Same HX as the 200 and no reset controls, but is it accurate that the Vitodens 100 and 200 are different boilers because the Vitodens 200 features the highly acclaimed Matrix Burner and the 100 does not?

Just wondering.

Paul

Hvacman

Knight is tops in my book...

I have many Knights installed in commercial settings and one going in my house, the only failures I've noted were due to controls programming (controls sub issue, no boiler) and one cracked condensate trap. I like the onboard controls package, high turndown, and efficiency... I'm pissed that a wallhung is coming out but I already bought the one for my house!

Tom Hopkins

Paul Rohrs_7

Wall Hung

The Knight wall hung will be a nice asset for Lochinvar. I saw the new unit at REX and it has two condensate lines feeding into the trap. (??) I know all of my questions will be answered soon as they are supposed to be coming off of the production line at the end of the month.

How many of you Knight installers are using their Pocket PC software? Invaluable little tool to have.

Paul

Perry_3

I'd like to retract my recomendation on using softened water..

Hot Rod is right about the problems that can occur with home water softning systems. Sometimes I forget as I am used to commercial watersofting where their is much better control.

I will repeat what he said in another post:

"Keep in mind copper and stainless steel boilers also have a tolerance level that can be exceeded. I'd shy away from softened water in a stainless boiler, knowing how poorly some softeners backwash the brine cycle

DI or DM water with the best hydronic conditioners is the proper way to protect your installs and the customers investment. You don't have a thick, heavy, bullet proof, cast iron vessel anymore when considering mod con choices

hot rod"

I agree; use DI or even distilled water (buy it by the gallon if needed); treat it with a good residential water treatment chemical to inhibit it; and don't worry. As long as your system is tight you will only get a few gallons of hard water into your system via the makeup system - which will not be a problem.

Have a great day all.

Perry

ScottMP

Installs

So Perry, how many installs have you done, besides your own ? Interesting to get such detailed advice from someone whos only done one install and not even the whole job. MAybe a little more experience under your belt before dispensing advice would help.

Tom Terrific.

ALH_4

100

I have not had the pleasure of working with a Vitodens 100, but I understand the heat exchanger is the same design as the Vitodens 200, but not the same passage size. I believe primary/secondary piping is absolutely required because of the more restrictive heat exchanger. Can anyone verify this?

Personally, I think the Vitodens 100 control is too stripped down. It doesn't need all the bells and whistles of the Comfortrol, but I would like to see outdoor reset built in. Also the size choices do not make a lot of sense to me. 3:1 turndown is a little disappointing, and a lower output model would be nice. A Vitodens 100 4-12 would have a real market in low-heat-loss homes.

Given a choice between the Knight and the Vitodens 200, I would choose the Vitodens 200. However, I think the Knight has to edge out the Vitodens 100, particularly because of the lack of built-in control.

Unknown

I'm psyched about a mod/con that doesn't have an outdoor reset control that I have to ignore when mounting the teknet 4 system on it

ALH_4

tN4

A benefit I hadn't considered, Rob. ;-)

My thoughts were that if you're connecting this to a system with TRV's, an internal reset control with WWSD is handy.

Unknown

You Luddites and your non-electric flow modulation!

How do you keep a mule cart stocked with boiler replacement parts anyway??

ALH_4

hydrono-primitivism.

I think I might need to upgrade to oxen, but that would put my mule out of a job. ;-)

Oh, the simple life...

Weezbo

Kevin, give Keller Supply a call.

ask them about the Knight installs and how they are being received in the community.

There are quite a few reputable out fits in Anchorage..

The Munchkins are all over the countryside there. Ferguson has a line or "feel" for the Viessmann .

one thing that you say is true that really does make a significant oops factor come into the general equation...Water quality.

that is one minor technicality that has caused many a product
grief
in your area. I would seriously consider having a separate water system feeding make up water into the system,and keeping up with the maint and thoroughly checking water samples from within the boiler...Hot Rod's advise is not something to breeze by.. there is a lot he is not saying written within what he is saying. GL

Kevin Callahan

Knights have been installed in Anchorage and are working well. No question in my mind the water (I am on a well, not city water) is an issue; I'll definitely put something other than my domestic water in the system; maybe deionized? This has also led me to wonder whether a TT Phase III or similar design would be the best answer for an indirect water heater rather than a coil type.

Andrew, I have a slightly different set of concerns about the Vitodens in my application. I don't really care about the controls (not quite a Luddite, but I'm the kind of person who prefers a viscous coupling all wheel drive to an electronic system). However, the turndown ratio is not as good as the Knight; the efficiency curve (at least going by the graph for the 200) is not as good at high temp/volume; and the adjustable setting stops at 176. This may work, but it could at least possibly max out my baseboard on the main floor on the very coldest days (-25), unless the boiler actually can go higher on demand. (Of course, I could add more baseboard, but the Knight goes to 190 and would not need this.)

In short, the Knight may be better suited for me in several respects. Against all this, however, are the recognized design and build quality, especially of the HE, and possibly longer life of the Vitodens.

ALH_4

AWD

I agree with your point about AWD. However, I would count thermostatic radiator valves as that viscous coupling and the outdoor reset controlled boiler as the engine throttle varied based on the load.

I agree that the Knight is better suited than is the Vitodens 100 to this type of operation. If we were considering the Vitodens 200, it might be a different story.

Truly you cannot go wrong with either of these high quality units.

I would not use deionized or distilled water to fill your system because it will then pick up ions from your system components and piping.

hot_rod

Di or DM

is fine do not use RO or distilled. It's too pure, so to speak. RO water will dissolve your copper pipe. True distilled water is only obtained by turning water to steam and collecting the condensate. a slow expensive procedure for large quantities. most of the distilled bottled water on the supermarket shelves is actually filtered DI or DM water. According to a local water company that sells it to them

Even with DI or DM water I would add a Rhomar or similar treatment. It puts back into the water only the good stuff after the filtered water procedure removes the bad stuff

You want a film provider. You want an O2 scavanger, and a ph buffer as most filtered water drops on the ph scale. This is what a hydronic conditioner adds back in.

This is also the reason glycols are blended with DI water, not tap water.

hot rod

Hvacman

I've got the...

Laptop version software, haven't played with it much though.

Josh M.

I'm with you Rob. I have been waiting for a "dumb" boiler priced effectively for a long time. I have already ordered 3 Vitodens 100's in anticipation of the 0-10V module coming out next month.

Fern

Ultra not failing

Hi I am up here in Canada and can tell you that if true primary/secondary piping arrangements are used and ph levels are to reuirements there are no failures that I know of!

Thanks,
Fern

Steve Ebels_3

Paul

I'm not familiar with the capabilities of the Pocket PC. What are the features that make it invaluable to you?

scott markle_2

di water

I read in a Heat link bulletin that distilled water is not recommended because it has the potential to leach metals into solution. My understanding is that distiled water seeks a mineral "balance" with it's environment,and will pull metals into solution from the system.

I asked the Rhomar people about this and they said that that the inhibitor product "blue juice" would take care of that issue. So I guess this would only be a potential problem if diluting glycol without adding additional inhibitor, or using straight distilled.

scott markle_2

related post

You might want to look over the flow vs.head post. It gets into some issues that relate directly to these boilers, specifically minimum boiler flow rates and the limitation that this can create.

Bob Flanagan_3

Hot Rod

Hot Rod:

Give me a call when you have a chance. I have a question that I'd like to ask you.

Thanks,
Bob Flanagan
V.P. Sales
Slant/Fin Corp.

Dave_4

Knight manual shows

primary loop pump as being installed on the return line to the boiler, also shows the indirect pump being on the return line from the indirect.

I thought that a pump is to be installed on the supply line, not the return.

How long has the Knight boiler been on the market.

Any thoughts on NTI Trinity boiler?

Pete

Paul Rohrs_4

Several Features I like....

#1. Ignition attempts.- Seems simple enough, but we had a commercial job (Replacement) that featured multiple boilers. Existing thermostats were creating communication issues and the PC software showed us an average of 150 ignition attempts a day.

#2. Save to File - I can compare data from a previously stored file. At an annual service, I can compare data with the previous year.

3#. Last 10 lockouts.

Regards,

PR

Unknown

circ on supply

Pete,

Correction, the primary pump is on the primary loop.
The diagram it shows the boiler pump and the DHW pump on the return pointing towrds the boiler. This is done on all mod-cons so you activate the sensitive pressure switch, Putthe boiler and DHW pump on the supply and you will likely have lockouts like we had on the early days of the munchkin :-)

skw